Type 1 diabetes (T1 D) is a tissue specific autoimmune disease characterized by the T mediated destruction of the insulin producing b cells of the islets of Langerhans. Treatment of diabetes has focused on the use of insulin replacement. However, this treatment can be difficult to regulate and has many shortcomings. While the surgical techniques for transplanting pancreatic islets is now at hand, problems remain. First and foremost is that fact that even syngeneic grafts are rejected due to the same autoimmune mechanisms that caused the initial islet cell loss. This process must be controlled to promote effective transplant function. Heretofore, most of the efforts in understanding the pathogenesis and treatment of T1D have focused on the role of CD4+ T cells. In this proposal we expand the current ideas of immunoregulation to CD8+ cells in T1D. We seek to study the repertoire and regulation of b cell specific CD8+ T cells, the role of CD8+ T cell subset, Tcl and Tc2 on regulation, and the roles of cytokines produced by CD4+ T cells in shaping the CD8+ T cell response. This will be accomplished by combing the use of MHC class I tetramers, peptides and novel immunization strategies. We will then use this information to deviate or anergize/delete peptide specific T cells and control the critical CD8+ T cell response in T1D to allow effective islet cell transplantation.